Form broaching and particularly slot broaching has been accomplished in the prior art with one-piece tooling in which individual teeth are ground into the tooling. Because of the limitations on the size of grinding wheels, it has been extremely difficult and costly to approximate the desired true form relief on the teeth of the tool.
The advantage of a broaching tooth with a true relief form all the way around the tooth is that the profile remains uniformly proportional when the cutter is sharpened. Furthermore, a smaller relief angle can be used due to the true form relief to allow more sharpenings before the size change exceeds part tolerances. The design also allows the use of carbide as a tool material for even greater tool life. This has not been possible in the one-piece design because of the difficulty in grinding carbide with the small grinding wheels necessary to grind the relief on one tooth without hitting the cutting edge of an adjacent tooth.
The individual cutters may each be made on computer numerical control (CNC) equipment to obtain the true form relief.
Another object and advantage of the invention lies in the tooth retaining assembly which provides accurate positioning and alignment of the individually ground teeth in a stepped hold-down block and wedge lock which cooperate to secure the teeth in a recessed holder.
Other objects and features of the invention will be apparent in the following description and claims in which the invention is described and details provided to enable persons skilled in the art to practice the invention, all in connection with the best mode presently contemplated.